Dosage counting devices

ABSTRACT

Apparatus comprising a housing ( 1 ) defining a portion ( 2 ) for receiving in use a dose-dispensing container ( 20 ), the housing containing a dose counter comprising at least one annular counter member ( 241, 242 ) and a helix-like coil ( 243 ), wherein one or more projections ( 255 ) are provided on the helix-like coil for operatively connecting the helix-like coil and the at least one annular counter member, wherein movement of the received dose-dispensing container acts to compress the helix-like coil to thereby rotate the at least one annular counter member.

[0001] The present invention relates to counting devices for use withdose-dispensing delivery apparatus which require an axial force foroperation.

[0002] It has been recognised that there is a need to provide accurateinformation to the user of a dose-dispensing delivery apparatusconcerning the number of doses delivered from, or remaining in, theapparatus. Without such accurate information there is the danger that auser will forget how many doses have been delivered and hence take agreater or fewer number of doses than is required. There is also thedanger that a user may be unaware that the delivery apparatus is emptyor close to empty. Hence, in an emergency situation, the user may seekto take a dose from the delivery apparatus only to find that there areno doses left in the apparatus. This is especially dangerous where thedelivery apparatus is for use in dispensing medicinal compounds for thetreatment of chronic or acute symptoms, for example, as in the case of apressurised metered dose inhaler used for treating asthmatic reactions.

[0003] A number of devices have been proposed to count the number ofdoses delivered or remaining in a delivery apparatus. WO95/08484 teachesa dose counting device for use with an aerosol medication dispenser. Thedevice works by translating a non-rotative force on an outer cover intoa rotation of an indicator wheel by use of a set of flexible pawlsengaged with a set of teeth. The pawls depress and thereby extendcircumferentially when the applied force forces them to effect arotation of the teeth. This device has, however, been found to havedisadvantages. The reliability of operation of the counting devicedepends on the relationship between the stiffness of the internal springbias of the medication dispenser and the pawls. If the pawls are toostiff relative to the internal spring bias then the medication dispensermay dispense a dose before the pawls flex sufficiently to rotate theindicator wheel; a dose wold be delivered without the counterregistering it. Alternatively, if the pawls are too flexible relative tothe internal spring bias then the pawls may flex sufficiently to rotatethe indicator wheel before the medication dispenser has dispensed adose; a dose would be registered by the counter but not actuallydelivered.

[0004] The present invention seeks to provide a dosage counting devicewhich overcomes these problems.

[0005] Accordingly, the present invention provides apparatus comprisinga housing defining a portion for receiving in use a dose-dispensingcontainer, the housing containing a dose counter comprising at least oneannular counter member and a helix-like coil, wherein one or moreprojections are provided on the helix-like coil for operativelyconnecting the helix-like coil and the at least one annular countermember, wherein movement of the received dose-dispensing container actsto compress the helix-like coil to thereby rotate the at least oneannular counter member.

[0006] The present invention also provides apparatus comprising ahousing defining a portion for receiving in use a dose-dispensingcontainer, the housing containing a dose counter comprising at least oneannular counter member, a helix-like coil having one or projections foroperatively connecting the helix-like coil and the at least one annularcounter member, and a support for supporting the at least one annularcounter member and helix-like coil in proper alignment with the receiveddose-dispensing container, wherein the support is an interference fit ina cap of the housing such that a first actuation of the receiveddose-dispensing container sets the position of the support relative tothe received dose-dispensing container and cap.

[0007] An embodiment of the present invention will now be described, byway of example only, with reference to the accompanying drawings, inwhich:

[0008]FIG. 1 is a cross-sectional view of a dispensing apparatusaccording to the present invention; and

[0009]FIG. 2 is an exploded perspective view of part of the dispensingapparatus of FIG. 1.

[0010] In the following description, the invention will be illustrated,by way of example only, with respect to a pressurised dispensingcontainer capable of delivering successive doses of a product in anaerosol form.

[0011]FIGS. 1 and 2 illustrate a dispensing apparatus according to thepresent invention.

[0012] The dispensing apparatus comprises a housing 1 having acylindrical portion 2 with upper and lower ends. The upper end 6 is openwhilst the lower end is closed off by a basal wall portion 7. Amouthpiece 3 which communicates with the cylindrical portion 2, dependslaterally from the lower end of the cylindrical portion 2. Themouthpiece 3 defines an outlet duct 4 which terminates in an outlet 5 ofthe mouthpiece 3.

[0013] An inwardly directed valve stem receiving block 9 is integrallyformed with the basal wall portion 7 and has its longitudinal axisaligned co-axially with a longitudinal axis of the cylindrical portion 2of the housing 1. The valve stem receiving block 9 defines a receivingbore 12 which is open to the cylindrical portion 2 and an orifice 10which is open to the outlet duct 4 of the mouthpiece 3. The receivingbore 12 and orifice 10 are linked by a duct 11.

[0014] Several, preferably six circumferentially spaced inwardlydirected longitudinal ribs 14 are provided on the internal wall of thecylindrical portion 2.

[0015] In use a pressurised dispensing container 20 is received in thecylindrical portion 2. The pressurised dispensing container 20 comprisesa canister body 21 defining a storage chamber for housing the product tobe dispensed. The canister body 21 is closed off at one end by ametering valve (not shown) having a valve stem 22 which extendsexternally from the metering valve. The metering valve is retained inthe canister body by a crimped ferrule 23.

[0016] When the pressurised dispensing container 20 is inserted into thehousing 1, the valve stem 22 is received in receiving bore 12 of thevalve stem receiving block 9. An annular air gap 13 exists between theinternal wall of the cylindrical portion 2 and the canister body 21 toallow air to flow through the dispensing apparatus in use.

[0017] According to the present invention a dosage counter is providedcomprising first and second indicator wheels 241, 242, a helical coil243 and support 246. The first and second indicator wheels 241, 242comprise indicia 247 marked on their peripheral walls. The firstindicator wheel 241 denotes numerical ‘units’ and the second indicatorwheel 242 denotes numerical ‘tens’. Each indicator wheel 241, 242 isannular.

[0018] The upper rim of the first indicator wheel 241 is formed into aseries of teeth which will be denoted as the upper teeth 248 of thefirst indicator wheel 241. In addition, the first indicator wheel 241comprises a series of internal teeth 249 arranged around a lower portionof the internal rim of the annulus. The first indicator wheel 241 alsocomprises three evenly distributed radial notches 250 on the upper halfof the internal rim of the annulus. Alternatively, two or more thanthree notches 250 may be provided.

[0019] The lower rim of the second indicator wheel 242 is formed into aseries of teeth which will be denoted as the lower teeth 270 of thesecond indicator wheel 242. The upper rim of the second indicator wheel242 is formed into a series of teeth which will be denoted as the upperteeth 251 of the second indicator wheel 242. In addition, the secondindicator wheel 242 comprises a series of internal teeth 252 arrangedaround a lower portion of the internal rim of the annulus.

[0020] The support 246 comprises an annular portion 262 from whichdepends an annular flange 263 whose lower face is formed into a seriesof teeth which will be denoted as the lower teeth 264 of the support246.

[0021] The helical coil 243 comprises an upper ring 253 and a lower-ring254 which are interconnected by two flexible helical struts 256. Thelower ring 254 comprises four equi-spaced radially outwardly directedprotrusions 255. The upper ring 253 is provided with at least one pairof upper and lower arms 260, 259 extending upwardly therefrom. Each armis provided with a laterally dependent finger portion forming a pawlwhich selectively engages the internal teeth 249, 252 of the first andsecond indicator wheels 241, 242 as described below. Two vertical struts257 depend from the upper ring 253 and extend partially towards thelower ring 254.

[0022] The first and second indicator wheels 241, 242, helical coil 243and support 246 are assembled within a cap 269. The cap 269 is generallycylindrical in shape and is closed off at an upper end. A window 8 isformed in a side wall near the upper end. Four longitudinally directedrecesses 261 are formed equi-spaced around the internal surface of thecap 269. An annular inwardly directed rim 273 is provided near the openend of the cap 269.

[0023] The dosage counter is assembled by first inserting the support246 into the cap 269. The support 246 forms a push-fit with the internalwall of the cap 269. The second indicator wheel 242, first indicatorwheel 241 and helical coil 243 are then inserted into the cap 269 inthat order. The four protrusions 255 of the lower ring 254 are receivedin the longitudinal recesses 261 of the cap 269. The components of thedosage counter are retained within the cap 269 by the interference ofthe lower ring 254 of the helical coil 243 and the annular rim 273 ofthe cap 269.

[0024] In the assembled position, the fingers 290 of the lower arms 259of are aligned with the internal teeth 249 of the first indicator wheel241. The fingers 291 of the upper arms 260 are partially aligned withthe internal teeth 252 of the second indicator wheel 242 and partiallyaligned with the upper half of the internal rim of the first indicatorwheel 241. Hence, the fingers 290 of the lower arms 259 are alwaysengaged with the internal teeth 249 of the first indicator wheel 241 butthe fingers 291 of the upper arms 260 are normally held out ofengagement with the internal teeth 252 of the second indicator wheel 242due to the presence of the internal rim of the first indicator wheel241.

[0025] The pressurised dispensing container 20 is received in thehousing 1. The cap 269 is then placed over the upper end of thepressurised dispensing container 20. A tubular extension 274 is providedwithin the cap 269 into which the canister body 21 forms a push-fit soas to retain the cap 269 in engagement with the housing 1. With the cap269 engaged with the housing 1, the lower ring 254 abuts and rests onthe upper end 6 of the cylindrical portion 2 of the housing 1 againstthe upper rim 300.

[0026] In use, a user operates the pressurised dispensing container 21by depressing the closed end of cap 269 axially to move it and thecanister body 21 relative to the cylindrical portion 2 of the housing 1.As a result, the valve stem 22 is inwardly retracted relative to themetering valve such that a dose of product is dispensed from the valvestem 22 into the bore 12 and duct 11 of the valve stem receiving block9. The product is then channelled by duct 11 and dispensed as an aerosolthrough orifice 10 into the outlet duct 4. The aerosol is inhaled by auser inhaling on outlet 5 of the mouthpiece 3. The support 246 is apush-fit within the cap 269 and therefore does not move axially during anormal operating cycle. Axial movement of the cap 269 causes the lowerring 254 to be compressed towards the upper ring 253 of the helical coil243. At the same time, due to the helical struts 256, the upper ring 253rotates relative to the lower ring 254 which cannot rotate relative tothe cap 269 due to the engagement of the protrusions 256 in thelongitudinal recesses 261.

[0027] As the upper ring 253 rotates, the first indicator wheel 241 isincrementally rotated due to engagement of the fingers 290 of the lowerarms 259 with the internal teeth 249.

[0028] The degree of axial movement of the upper ring 253 relative tothe lower ring 254 is limited by the vertical struts 257 which groundagainst the lower ring 254.

[0029] After successive rotations of the first indicator wheel 241 thefingers 291 of the upper arms 260 are brought into alignment with theradial notches 250 of the first indicator wheel 241. As a consequence,the fingers 291 of the upper arms 160 can flex radially outwards so asto engage the internal teeth 252 of the second indicator wheel 242.Consequently, the second indicator wheel 242 rotates one increment onthe next actuation of the metering valve. In this way, the ‘tens’indicia can be incremented once for every ten increments of the ‘units’indicia.

[0030] On release of the canister body 21 by the user, the pressuriseddispensing container 20 returns to its rest position as described above.At the same time, the helical coil 243 recovers to its original shape.The angling of the fingers 290, 291 of the upper and lower arms 260,259, and the teeth of the support 246 and first and second indicatorwheels 241, 242 prevents any reverse movement of the indicator wheels241, 242 during this part of the operating cycle.

[0031] The dosage counter is ‘set’ in the cap 269 on the first actuationas follows:

[0032] The support 246 is assembled in the cap 269 at a point below itsnormal operating position, i.e., nearer the open end of the cap thanshown in FIG. 1.

[0033] Consequently, the first and second indicator wheels 241, 242 andhelical coil 243 are all also nearer the open end than their normaloperating positions. On the first actuation, which may be undertaken bythe user or at the point of manufacture or sale, the upper rim 300 atthe upper end 6 of the housing 1 initially compresses the helical coil243 without moving the support 246. Once the helical coil 243 has beencompressed such that the vertical struts 257 have contacted the lowerring 254 (during which movement the metering valve is actuated), theuser, pharmacist or manufacturer applies a higher axial force to the cap269 to move both the helical coil 243 and support 246 axially relativeto the cap 269 until the retracted valve stem 22 ‘grounds’ against thebase of the receiving bore 12 of the valve stem receiving block 9. Thesupport 246 is now in its normal operating position and is ‘set’. Thesetting of the support 246 takes into account any variations in distancebetween the upper rim 300 at the upper end 6 of the housing 1 and theend of the valve stem 22. Without this feature, it is possible forvariations in pressurised dispensing containers to mean that in certaincircumstances, the metering valve may be actuated before the firstindicator wheel 241 rotates or vice versa.

1. Apparatus comprising a housing defining a portion for receiving inuse a dose-dispensing container, the housing containing a dose countercomprising at least one annular counter member and a helix-like coil,wherein one or more projections are provided on the helix-like coil foroperatively connecting the helix-like coil and the at least one annularcounter member, wherein movement of the received dose-dispensingcontainer acts to compress the helix-like coil to thereby rotate the atleast one annular counter member.
 2. Apparatus as claimed in claim 1wherein the helix-like coil comprises an upper ring, a lower ring and atleast one strut spanning between the upper and lower rings.
 3. Apparatusas claimed in claim 2 wherein the at least one strut is helicallyshaped.
 4. Apparatus as claimed in claim 2 or claim 3 wherein one of theupper or lower rings of the helix-like coil comprises one or moreprojections orientated towards the other of the upper or lower rings tothereby limit the movement of the upper and lower rings towards oneanother.
 5. Apparatus as claimed in any preceding claim wherein each ofthe at least one annular counter members comprise a first series ofteeth, the projections of the helix-like coil being selectivelyengagable with each of the first series of teeth such that rotationalmovement of the helix-like coil causes the at least one annular countermember to rotate relative to the housing in a first direction. 6.Apparatus as claimed in claim 5 wherein the first series of teeth areformed around an inner rim of the at least one annular counter members.7. Apparatus as claimed in any preceding claim wherein the dose countercomprises two or more annular counter members.
 8. Apparatus as claimedin any preceding claim wherein the housing comprises a cap.
 9. Apparatusas claimed in claim 8 further comprising a support slidably received inthe cap to support the at least one annular counter member andhelix-like coil in proper alignment.
 10. Apparatus as claimed in claim 8or claim 9 wherein the lower ring of the helix-like coil contacts anupper end of the dose-dispensing container receiving portion of thehousing.
 11. Apparatus as claimed in claim 9 or claim 10 wherein asurface of the support is formed into a series of teeth engagable with asecond series of teeth formed on the second annular counter member, soas to prevent rotation of the annular counter members in a directionopposed to the first direction.
 12. Apparatus as claimed in any ofclaims 5 to 11 wherein the helix-like coil comprises at least oneratchet engagable with the first series of teeth formed on each of theannular counter members, so as to prevent rotation of the annularcounter members in a direction opposed to the first direction. 13.Apparatus as claimed in claim 12 wherein a bearing surface is providedforming at least part of the inner rim of the first annular countingmember to selectively hold the projections out of engagement with thefirst series of teeth of the second annular counter member, the bearingsurface comprising at least one indent allowing movement of theprojections radially outwardly into engagement with the first series ofteeth of the second annular counter member after a pre-determined numberof incremental rotations of the first annular counter member. 14.Apparatus as claimed in any of claims 7 to 13 wherein the first annularcounter member is driven to incrementally rotate in the first directionon each actuation of the received dose-dispensing container and thesecond annular counter member is driven to incrementally rotate in thefirst direction only after a pre-determined number of incrementalrotations of the first annular counter member.
 15. Apparatus comprisinga housing defining a portion for receiving in use a dose-dispensingcontainer, the housing containing a dose counter comprising at least oneannular counter member, a helix-like coil having one or projections foroperatively connecting the helix-like coil and the at least one annularcounter member, and a support for supporting the at least one annularcounter member and helix-like coil in proper alignment with the receiveddose-dispensing container, wherein the support is an interference fit ina cap of the housing such that a first actuation of the receiveddose-dispensing container sets the position of the support relative tothe received dose-dispensing container and cap.
 16. Apparatussubstantially as hereinbefore described with reference to and as shownin the accompanying drawings.